iTunes slow to read from SD Card in Macbook Air

I've recently bought a Macbook Air and I'm using a 64GB SD card to store my iTunes library there, so iTunes is constantly reading from the SD Card. The first times I used it I was quite disappointed, as there was a very important (1-2s) delay when switching between songs, which doesn't happen for example in other computers or my car which has an SD reader slot. However, the other day for no aparent reason the SD card was behaving incredibly fast, switching songs was instantaneous, but today I'm back to the old slow speeds.

Is there some reason why the SD card is fast or slow to read in different scenarios? I haven't plugged in anything to the USB port that could be hogging the USB bus.

Ok, I've isolated the problem and it only happens with mp3 files, not with AAC files. This is incredibly annoying because 90% of my music is in mp3 format. AAC plays immediately with no lag whatsoever :S

Ok, I've isolated the problem and it only happens with mp3 files, not with AAC files. This is incredibly annoying because 90% of my music is in mp3 format. AAC plays immediately with no lag whatsoever :S

Notice that this thread is 4 years old. I used to have a 2011 MBA and the SD card slot was really slow, regardless of card type. The slot on these older machines was actually connected to the USB 2.0 bus. In 2012 Apple changed the design and gave the card slot a much faster interface.

My 2013 MBA is still "relatively slow" when using an SD card. 700 meg/sec read/write to internal storage, 60 meg read & 85 meg write to the SD, formatted either hfs or exfat. Sure, it's an old thread but what the heck?

MacRumors attracts a broad audience
of both consumers and professionals interested in
the latest technologies and products. We also boast an active community focused on
purchasing decisions and technical aspects of the iPhone, iPod, iPad, and Mac platforms.